Don't jump to conclusions — it's likely that your mom loves both you and your brother equally!
Obviously, I haven't got the full picture so I can't say for sure, but it's easy to feel as if your sibling is loved more than you. If this is upsetting you, I think you should talk to your mom about it, when your brother isn't around.
Don't Blame Your Brother
The last thing you want to do is grow up with a grudge against your brother — it's not his fault, even if (although I doubt this) your mother likes him more.
I've experienced this myself, and I really regret it. My relationship with my brother has definitely suffered from the way my dad treated us. He's a complete misogynist and always spent a lot of time and money on my brother, and none on me. I don't talk to my dad any more, but the thing I regret most is that I grew up hating my brother for something that wasn't his fault. Don't let this happen to you.
It's Not Your Fault, Either
If you feel that your mom does prefer your brother, please don't think that it's your fault, or that there's something wrong with you. You're not inadequate, or a disappointment, or a failure. Don't let your fears about what your mother thinks of you stop you from achieving your potential.
I really think you should discuss this with your mom. She'll probably reassure you that this isn't the case at all, and that you've got it all wrong. If she doesn't, then she is the one with the issues, not you.
Take care, and try to see this from everybody's point of view! Good luck.